Current photoelectric smoke detection technologies and products are several decades old. The basic principle includes the use of a light emitter (nowadays usually IR led) and a light sensitive receiver (usually PIN photodiode) placed out of sight each other.
The emitter is energized, or pulsed, periodically. When smoke is present the receiver detects the increasing scattered light signal. A photocurrent to voltage circuit (transimpedance amplifier) is usually used to measure smoke presence and eventually determine alarm condition.
The main strengths of this technology are low cost simplicity, fairly broad applicability and low power consumption. The weakness of the approach are poor nuisance immunity (dust, steam, etc., might set the detector in alarm), difficult to detect very small and/or dark absorbing particles such as those coming from some flaming fires (which usually requires Ion detectors). An optical detector covering the product range usually covered by ion detectors would be a benefit under the production, storage, installation, maintenance and end of life management perspective.
There thus is a need for approaches to photoelectric smoke detection which take advantage of currently available components. Preferably, using such components, more sensitive, nuisance immune, detectors could be produced. It would also be desirable if costs were comparable to those of existing photoelectric detectors.